640721620000 has 720 divisors, whose sum is σ = 2004034253760. Its totient is φ = 197303040000.

The previous prime is 640721619959. The next prime is 640721620001. The reversal of 640721620000 is 26127046.

It is a Harshad number since it is a multiple of its sum of digits (28).

It is not an unprimeable number, because it can be changed into a prime (640721620001) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 119 ways as a sum of consecutive naturals, for example, 1846459827 + ... + 1846460173.

It is an arithmetic number, because the mean of its divisors is an integer number (2783380908).

Almost surely, 2^640721620000 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 640721620000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1002017126880).

640721620000 is an abundant number, since it is smaller than the sum of its proper divisors (1363312633760).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

640721620000 is a wasteful number, since it uses less digits than its factorization.

640721620000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 515 (or 481 counting only the distinct ones).

The product of its (nonzero) digits is 4032, while the sum is 28.

Adding to 640721620000 its reverse (26127046), we get a palindrome (640747747046).

The spelling of 640721620000 in words is "six hundred forty billion, seven hundred twenty-one million, six hundred twenty thousand".